Semiautomatic, as well as automatic pistols comprise usually a bolt or obturator which is guidedly capable of operational, longitudinal movements or displacements, back and forth along and on the body of the firearm. Further, the bolt or obturator is provided, usually on its front or anterior part, with an arresting or blocking portion which interacts with a fixed shoulder provided on the body itself, so as to limit the retro movement of the bolt. On the other hand, the forward movement of the bolt is limited by its support, when in the closed position.
Now, unexpected or accidental causes or reasons, such as the incorrect use of the pistol, the careless maintenance thereof, the employment of improper ammunition or of cartridges with excessive charge, etc. may be a source of cracks or faulty lines, which as time goes on result in the breaking of the bolt. The breakage may occur in areas of lesser resistance, such as those in the back of the arresting means which limit the retro movement of the bolt. In such a case, the normal arresting means provided on the bolt are insufficient to prevent that the rear portion thereof, no longer held, be violently projected rearwardly when the projectile that causes the final ultimate breakage of the bolt is fired, with the attendant danger to the user of the pistol. Hence, the need to provide this type of pistols with means which can prevent such an occurrence, in the event that the bolt be broken, and keep the user physical injury.